Cholera and Vibrio choleraeClinical Manifestations: Cholera is a potentially epidemic and life-threatening secretory diarrhea characterized by numerous, voluminous watery stools, often accompanied by vomiting, and resulting in hypovolemic shock and acidosis. It is caused by certain members of the species Vibrio cholerae which can also cause mild or inapparent infections. Other members of the species may occasionally cause isolated outbreaks of milder diarrhea whereas others—the vast majority—are free-living and not associated with disease.

Structure, Classification, and Antigenic Types: Vibrios are Gram-negative, highly motile curved rods with a single polar flagellum. They tolerate alkaline media that kill most intestinal commensals, but they are sensitive to acid. Numerous free-living vibrios are known, some potentially pathogenic. Until 1992, cholera was caused by only two serotypes, Inaba (AC) and Ogawa (AB), and two biotypes, classical and El Tor, of toxigenic O group 1 V cholerae. These organisms may be identified by agglutination in O group 1-specific antiserum directed against the lipopolysaccharide component of the cell wall and by demonstration of their enterotoxigenicity. In 1992, cholera caused by serogroup O139 (synonym “Bengal” the 139th and latest serogroup of V cholerae to be identified) emerged in epidemic proportions in India and Bangladesh. This serovar is identified by 1) absence of agglutination in O group 1 specific antiserum; 2) by agglutination in O group 139 specific antiserum; and 3) by the presence of a capsule.

Pathogenesis: Cholera is transmitted by the fecal-oral route. Vibrios are sensitive to acid, and most die in the stomach. Surviving virulent organisms may adhere to and colonize the small bowel, where they secrete the potent cholera enterotoxin (CT, also called “choleragen”). This toxin binds to the plasma membrane of intestinal epithelial cells and releases an enzymatically active subunit that causes a rise in cyclic adenosine 51-monophosphate (cAMP) production. The resulting high intracellular cAMP level causes massive secretion of electrolytes and water into the intestinal lumen.

Epidemiology: Cholera is endemic or epidemic in areas with poor sanitation; it occurs sporadically or as limited outbreaks in developed countries. In coastal regions it may persist in shellfish and plankton. Long-term convalescent carriers are rare. Enteritis caused by the halophile V parahaemolyticus is associated with raw or improperly cooked seafood.

Diagnosis: The diagnosis is suggested by strikingly severe, watery diarrhea. For rapid diagnosis, a wet mount of liquid stool is examined microscopically. The characteristic motility of vibrios is stopped by specific antisomatic antibody. Other methods are culture of stool or rectal swab samples on TCBS agar and other selective and nonselective media; the slide agglutination test of colonies with specific antiserum; fermentation tests (oxidase positive); and enrichment in peptone broth followed by fluorescent antibody tests, culture, or retrospective serologic diagnosis. More recently the polymerase chain reaction (PCR) and additional genetically-based rapid techniques have been recommended for use in specialized laboratories.

Control: Control by sanitation is effective but not feasible in endemic areas. A good vaccine has not yet been developed. A parenteral vaccine of whole killed bacteria has been used widely, but is relatively ineffective and is not generally recommended. An experimental oral vaccine of killed whole cells and toxin B-subunit protein is less than ideal. Living attenuated genetically engineered mutants are promising, but such strains can cause limited diarrhea as a side effect. Antibiotic prophylaxis is feasible for small groups over short periods.

Other Vibrio Infections:

Other serogroups of V cholerae may cause diarrheal disease and other infections but are not associated with epidemic cholera. Vibrio parahaemolyticus is an important cause of enteritis associated with the ingestion of raw or improperly prepared seafood. Other Vibrio species, including V vulnificus, can cause infections of humans and other animals including fish. Campylobacter species (formerly included with vibrios) can cause enteritis. C pylori, now known as Helicobacter pylori, is associated with gastric and duodenal ulcers (see Ch. 23).

Introduction

Vibrios are highly motile, gram-negative, curved or comma-shaped rods with a single polar flagellum. Of the vibrios that are clinically significant to humans, Vibrio cholerae O group 1, the agent of cholera, is the most important. Vibrio cholerae was first isolated in pure culture by Robert Koch in 1883, although it had been seen by other investigators, including Pacini, who is credited with describing it first in Florence, Italy, in 1854.

Cholera is a life-threatening secretory diarrhea induced by an enterotoxin secreted by V cholerae. Cholera and the cholera enterotoxin are increasingly recognized as the prototypes for a wide variety of non-invasive diarrheal diseases, collectively known as the enterotoxic enteropathies; of these, diarrhea due to enterotoxigenic strains of Escherichia coli (see Ch. 26) is the most important. Cholera remains a major epidemic disease. There have been seven great pandemics. The latest, which started in 1961, invaded the Western Hemisphere (for the first time this century) with a massive outbreak in Peru in 1991. There have since been more than a million cases in Central and South America as well as a few imported cases in the U.S. and Canada. V cholerae serogroup O139, which arose in October of 1992 in India and Bangladesh, may become the cause of the 8th great pandemic of cholera.

Other vibrios may also be clinically significant in humans, and some are known to cause diseases in domestic animals. Nonpathogenic vibrios are widely distributed in the environment, particularly in estuarine waters and seafoods. For this reason, isolation of a vibrio from a patient with diarrheal disease does not necessarily indicate an etiologic relationship.

Vibrio Cholerae

Clinical Manifestations

Following an incubation period of 6 to 48 hours, cholera begins with the abrupt onset of watery diarrhea (Fig. 24-1). The initial stool may exceed 1 L, and several liters of fluid may be secreted within hours, leading to hypovolemic shock. Vomiting usually accompanies the diarrheal episodes. Muscle cramps may occur as water and electrolytes are lost from body tissues. Loss of skin turgor, scaphoid abdomen, and weak pulse are characteristic of cholera. Various degrees of fluid and electrolyte loss are observed, including mild and subclinical cases. The disease runs its course in 2 to 7 days; the outcome depends upon the extent of water and electrolyte loss and the adequacy of water and electrolyte repletion therapy. Death can occur from hypovolemic shock, metabolic acidosis, and uremia resulting from acute tubular necrosis.

The cholera vibrios are Gram-negative, slightly curved rods whose motility depends on a single polar flagellum. Their nutritional requirements are simple. Fresh isolates are prototrophic (i.e., they grow in media containing an inorganic nitrogen source, a utilizable carbohydrate, and appropriate minerals). In adequate media, they grow rapidly with a generation time of less than 30 minutes. Although they reach higher population densities when grown with vigorous aeration, they can also grow anaerobically. Vibrios are sensitive to low pH and die rapidly in solutions below pH 6; however, they are quite tolerant of alkaline conditions. This tolerance has been exploited in the choice of media used for their isolation and diagnosis.

Until 1992, the vibrios that caused epidemic cholera were subdivided into two biotypes: classical and El Tor. Classical V cholerae was first isolated by Koch in 1883. Subsequently, in the early 1900s, some vibrios resembling V cholerae were isolated from Mecca-bound pilgrims at the quarantine station at El Tor, in the Sinai peninsula, that had been established to try to control cholera associated with pilgrimages to Mecca. These vibrios resembled classical V cholerae in many ways but caused lysis of goat or sheep erythrocytes in a test known as the Greig test. Because the pilgrims from whom they were isolated did not have cholera, these hemolytic El Tor vibrios were regarded as relatively insignificant except for the possibility of confusion with true cholera vibrios. In the 1930s, similar hemolytic vibrios were associated with relatively restricted outbreaks of diarrheal disease, called paracholera, in the Celebes. In 1961, cholera caused by El Tor vibrios erupted in Hong Kong and spread virtually worldwide. Although in the course of this pandemic most V cholerae biotype El Tor strains lost their hemolytic activity, a number of ancillary tests differentiate them from vibrios of the classical biotype.

The operational serology of the cholera vibrios which belong in O antigen group 1 is relatively simple. Both biotypes (El Tor and classical) contain two major serotypes, Inaba and Ogawa (Fig. 24-2). These serotypes are differentiated in agglutination and
vibriocidal antibody tests on the basis of their dominant heat-stable lipopolysaccharide somatic antigens. The cholera group has a common antigen, A, and the serotypes are differentiated by the type-specific antigens, B (Ogawa) and C (Inaba). An additional serotype, Hikojima, which has both specific antigens, is rare. V cholerae O139 appears to have been derived from the pandemic El Tor biotype but has lost the characteristic O1 somatic antigen; it has gained the ability to produce a polysaccharide capsule; it produces the same cholera enterotoxin; and it seems to have retained the epidemic potential of O1 strains.

Other antigenic components of the vibrios, such as outer membrane protein antigens, have not been extensively studied. The cholera vibrios also have common flagellar antigens. Cross-reactions with Brucella and Citrobacter species have been reported. Because of DNA relatedness and other similarities, other vibrios formerly called “nonagglutinable” are now classified as V cholerae. The term nonagglutinable is a misnomer because it implies that these vibrios are not agglutinable; in fact, they are not agglutinable in antisera against the O antigen group 1 cholera vibrios, but they are agglutinable in their own specific antisera. More than 139 serotypes are now recognized. Some strains of non-O group 1 V cholerae cause diarrheal disease by means of an enterotoxin related to the cholera enterotoxin and, perhaps, by other mechanisms, but these strains have not been associated with devastating outbreaks like those caused by the true cholera vibrios. Recently, vibrio strains that agglutinate in some O group 1 cholera diagnostic antisera but not in others have been isolated from environmental sources. Volunteer feeding experiments have shown that these atypical O group 1 vibrios are not enteropathogenic in humans. Recent studies using specific toxin gene probes indicate that these environmental isolates not only are nontoxigenic, but also do not possess any of the genetic information encoding cholera toxin, although some isolates from diarrheal stools do.

The cholera vibrios cause many distinctive reactions. They are oxidase positive. The O group 1 cholera vibrios almost always fall into the Heiberg I fermentation pattern; that is, they ferment sucrose and mannose but not arabinose, and they produce acid but not gas. Vibrio cholerae also possesses lysine and ornithine decarboxylase, but not arginine dihydrolase. Freshly isolated agar-grown vibrios of the El Tor biotype, in contrast to classical V cholerae, produce a cell-associated mannose-sensitive hemagglutinin active on chicken erythrocytes. This activity is readily detected in a rapid slide test. In addition to hemagglutination, numerous tests have been proposed to differentiate the classical and El Tor biotypes, including production of a hemolysin, sensitivity to selected bacteriophages, sensitivity to polymyxin, and the Voges-Proskauer test for acetoin. El Tor vibrios originally were defined as hemolytic. They differed in this characteristic from classical cholera vibrios; however, during the most recent pandemic, most El Tor vibrios (except for the recent isolates from Texas and Louisiana) had lost the capacity to express the hemolysin. Most El Tor vibrios are Voges-Proskauer positive and resistant to polymyxin and to bacteriophage IV, whereas classical vibrios are sensitive to them. As both biotypes cause the same disease, these characteristics have only epidemiologic significance. Strains of the El Tor biotype, however, produce less cholera enterotoxin, but appear to colonize intestinal epithelium better than vibrios of the classical variety. Also, they seem some what more resistant to environmental factors. Thus, El Tor strains have a higher tendency to become endemic and exhibit a higher infection-to-case ratio than the classical biotype.

Pathogenesis

Recent studies with laboratory animal models and human volunteers have provided a detailed understanding of the pathogenesis of cholera. Initial attempts to infect healthy American volunteers with cholera vibrios revealed that the oral administration of up to 1011 living cholera vibrios rarely had an effect; in fact, the organisms usually could not be recovered from stools of the volunteers. After the administration of bicarbonate to neutralize gastric acidity, however, cholera diarrhea developed in most volunteers given 104 cholera vibrios. Therefore, gastric acidity itself is a powerful natural resistance mechanism. It also has been demonstrated that vibrios administered with food are much more likely to cause infection.

Cholera is exclusively a disease of the small bowel. To establish residence and multiply in the human small bowel (normally relatively free of bacteria because of the effective clearance mechanisms of peristalsis and mucus secretion), the cholera vibrios have one or more adherence factors that enable them to adhere to the microvilli (Fig. 24-3). Several hemagglutinins and the toxin-coregulated pili have been suggested to be involved in adherence but the actual mechanism has not been defined. In fact, there may be multiple mechanisms. The motility of the vibrios may affect virulence by enabling them to penetrate the mucus layer. They also produce mucinolytic enzymes, neuraminidase, and proteases. The growing cholera vibrios elaborate the cholera enterotoxin (CT or choleragen), a polymeric protein (Mr 84,000) consisting of two major domains or regions. The A region (Mr 28,000), responsible for biologic activity of the enterotoxin, is linked by noncovalent interactions with the B region (Mr 56,000), which is composed of five identical noncovalently associated peptide chains of Mr 11,500. The B region, also known as choleragenoid, binds the toxin to its receptors on host cell membranes. It is also the immunologically dominant portion of the holotoxin. The structural genes that encode the synthesis of CT reside on a transposon-like element in the V cholerae chromosome, in contrast to those for the heat-labile enterotoxins (LTs) of E coli (Ch. 25), which are encoded by plasmids. The amino acid sequences of these structurally, functionally, and immunologically related enterotoxins are very similar. Their differences account for the differences in physicochemical behavior and the antigenic distinctions that have been noted. There are at least two antigenically related but distinct forms of cholera enterotoxin, called CT-1 and CT-2. Classical O1 V cholerae and the Gulf Coast El Tor strains produce CT-1 whereas most other El Tor strains and O139 produce CT-2. Vibrio cholerae exports its enterotoxin, whereas the E coli LTs occur primarily in the periplasmic space. This may account for the reported differences in severity of the diarrheas caused by these organisms.

Figure 24-3
Vibrio cholerae attachment and colonization in experimental rabbits. The events are assumed to be similar in human cholera. (A) Scanning electron microscopy during early infection. Curved (more…)

Studies in adult American volunteers have shown that 5µ g of CT, administered orally with bicarbonate, causes 1 to 6 L of diarrhea; 25µg causes more than 20 L.

Synthesis of CT and other virulence-associated factors such as toxin-coregulated pili are believed to be regulated by a transcriptional activator, Tox R, a transmembrane DNA-binding protein.

The molecular events in these diarrheal diseases involve an interaction between the enterotoxins and intestinal epithelial cell membranes (Fig. 24-4). The toxins bind through region B to a glycolipid, the GM1 ganglioside, which is practically ubiquitous in eukaryotic cell membranes. Following this binding, the A region, or a major portion of it known as the A1 peptide (Mr 21,000), penetrates the host cell and enzymatically transfers ADP-ribose from nicotinamide adenine dinucleotide (NAD) to a target protein, the guanosine 5′-triphosphate (GTP)-binding regulatory protein associated with membrane-bound adenylate cyclase. Thus, CT (and LT) resembles diphtheria toxin in causing transfer of ADP-ribose to a substrate. With diphtheria toxin, however, the substrate is elongation factor 2 and the result is cessation of host cell protein synthesis. With CT, the ADP-ribosylation reaction essentially locks adenylate cyclase in its “on mode” and leads to excessive production of cyclic adenosine 51-monophosphate (cAMP). Pertussis toxin, another ADP-ribosyl transferase, also increases cAMP levels, but by its effect on another G-protein, Gi (Fig. 24-5).

The subsequent cAMP-mediated cascade of events has not yet been delineated, but the final effect is hypersecretion of chloride and bicarbonate followed by water, resulting in the characteristic isotonic voluminous cholera stool. In hospitalized patients, this can result in losses of 20 L or more of fluid per day. The stool of an actively purging, severely ill cholera patient can resemble rice water—the supernatant of boiled rice. Because the stool can contain 108 viable vibrios per ml, such a patient could shed 2 × 1012 cholera vibrios per day into the environment. Perhaps by production of CT, the cholera vibrios thus ensure their survival by increasing the likelihood of finding another human host. Recent evidence suggests that prostaglandins may also play a role in the secretory effects of cholera enterotoxin. Recent studies in volunteers using genetically-engineered Tox– strains of V cholerae have revealed that the vibrios have putative mechanisms in addition to CT for causing (milder) diarrheal disease. These include Zot (for Zonula occludens toxin) and Ace (for accessory cholera enterotoxin), and perhaps others, but their role has not been established conclusively. Certainly CT is the major virulence factor and the act of colonization of the small bowel may itself elicit an altered host response (e.g., mild diarrhea), perhaps by a trans-membrane signaling mechanism.

Figure 24-5
Comparison of activities of cholera enterotoxin (CT) with pertussis toxin (PT). The α-subunits of Gs and Gi, with GTP-binding sites, are ADP-ribosylated, respectively, by A1 (more…)

Various animal models have been used to investigate pathogenic mechanisms, virulence, and immunity. Ten-day-old suckling rabbits develop a fulminating diarrheal disease after intraintestinal inoculation with virulent V cholerae or CT. Adult rabbits are relatively resistant to colonization by cholera vibrios; however, they do respond, with characteristic out pouring of fluid, to the intraluminal inoculation of live vibrios or enterotoxin in surgically isolated ileal loops. Suckling mice are susceptible to intragastric inoculation of vibrios and to orally administered toxin. Adult conventional mice are also susceptible to orally administered toxin, but resist colonization except in isolated intestinal loops. Interestingly, however, germ-free mice can be colonized for months with cholera vibrios. They rarely show adverse effects, although they are susceptible to cholera enterotoxin. Dogs have been used experimentally, although they are relatively refractory and require enormous inocula to elicit choleraic manifestations. Chinchillas also are susceptible to diarrhea following intraintestinal inoculation with moderate numbers of cholera vibrios. Infections initiated by extraintestinal routes of inoculation (e.g., intraperitoneal) largely reflect the toxicity of the lipopolysaccharide endotoxin. The intraperitoneal infection in mice has been used to assay the protective effect of conventional killed vibrio vaccines (no longer widely used).

Various animals, including humans, rabbits, and guinea pigs, also respond to intradermal inoculation of relatively minute amounts of CT with a characteristic delayed (maximum response at 24 hours), sustained (visible up to 1 week or more), erythematous, edematous induration associated with a localized alteration of vascular permeability. In laboratory animals, this response can be measured after injecting a protein-binding dye, such as trypan blue, that extravasates to produce a zone of bluing at the site of intracutaneous inoculation of toxin. This observation has been exploited in the assay of CT and its antibody and in the detection of other enterotoxins.

In addition, because of the broad spectrum of activity of CT on cells and tissues that it never contacts in nature, various in vitro systems can be used to assay the enterotoxin and its antibody. In each, the toxin causes a characteristically delayed, but sustained, activation of adenylate cyclase and increased production of cAMP, and it may cause additional, readily recognizable, morphologic alterations of certain cultured cell lines. The cells most widely used for this purpose are Chinese hamster ovary (CHO) cells, which elongate in response to picogram doses of the toxin, and mouse Y-l adrenal tumor cells, which round up. Cholera toxin has become an extremely valuable experimental probe to identify other cAMP-mediated responses. It also activates adenylate cyclase in pigeon erythrocytes, a procedure that was used by D. Michael Gill to define its mode of action.

These assays and models also have been applied in the study of an expanding number of CT-related and unrelated enterotoxins. These include the LTs of E coli, which are structurally and immunologically similar to it and are effective in any model that is responsive to CT. The family of small molecular weight heat-stable enterotoxins (ST) of E coli, which activate guanylate cyclase, and which are rapidly active in the infant mouse and certain other intestinal models, are clearly unrelated to CT. CT-related enterotoxins have been reported from certain nonagglutinable (non-O group I) Vibrio strains and a Salmonella enterotoxin was shown to be related immunologically to CT. CT-like factors from Shigella and V parahaemolyticus have thus far been demonstrated only in sensitive cell culture systems. Other enterotoxins and enterocytotoxins, which elicit cytotoxic effects on intestinal epithelial cells, also have been described from Escherichia, Klebsiella, Enterobacter, Citrobacter, Aeromonas, Pseudomonas, Shigella, V parahaemolyticus, Campylobacter, Yersinia enterocolitica, Bacillus cereus, Clostridium perfringens, C difficile, and staphylococci. Escherichia coli, some vibrio strains, and some other enteric bacteria produce cytotoxins that, like Shiga toxin of Shigella dysenteriae, act on Vero (African green monkey kidney) cells in vitro. These toxins have been called Shiga-like toxins, Shiga toxin-like toxins, Vero toxins, and Vero cytotoxins. The classic staphylococcal enterotoxins perhaps should more properly be called neurotoxins, as they seem to affect the central nervous system rather than the gut directly to cause fluid secretion or histopathologic effects.

Host Defenses

Infection with cholera vibrios results in a spectrum of responses. These range from no observed manifestations except perhaps a serologic response ( the most common) to acute purging, which must be treated by hospitalization and fluid replacement therapy; this is the classic response. The reasons for these differences are not entirely clear, although it is known that individuals differ in gastric acidity and that hypochlorhydric individuals are most prone to cholera. Whether individuals differ in the availability of intestinal receptors for cholera vibrios or for their toxin has not been established. Prior immunologic experience of subjects at risk is certainly a major factor. For example, in heavily endemic regions such as Bangladesh, the attack rate is relatively low among adults in comparison with children. In neoepidemic areas, cholera is more frequent among the working adult population. Resistance is related to the presence of circulating antibody and, perhaps more importantly, local immunoglobulin A (IgA) antibody against the cholera bacteria or the cholera enterotoxin or both. Intestinal IgA antibody can prevent attachment of the vibrios to the mucosal surface and neutralize or prevent binding of the cholera enterotoxin. For reasons that are not clear, individuals of blood group O are slightly more susceptible to cholera. Breastfeeding is highly recommended as a means of increasing immunity of infants to this and other diarrheal disease agents.

Recovery from cholera probably depends on two factors: elimination of the vibrios by antibiotics or the patient’s own immune response, and regeneration of the poisoned intestinal epithelial cells. Treatment with a single 200-mg dose of doxycycline has been recommended. As studies in volunteers demonstrated conclusively, the disease is an immunizing process. Patients who have recovered from cholera are solidly immune for at least 3 years.

Cholera vaccines consisting of killed cholera bacteria administered parenterally have been used since the turn of the century. However, recent controlled field studies indicate that little, if any, effective immunity is induced in immunologically virgin populations by such vaccines, although they do stimulate preexisting immunity in the adult population in heavily endemic regions. Controlled studies have likewise shown that a cholera toxoid administered parenterally was ineffective in preventing cholera. Probably the natural disease should be simulated to induce truly effective immunity although a parenterally administered conjugate vaccine consisting of the polysaccharide of the vibrio LPS covalently linked to cholera toxin has given promising results in preliminary studies. Studies in volunteers have shown that orally administered, chemically mutagenized or genetically engineered mutants which do not produce CT or produce only its B subunit protein can induce immunity against subsequent challenge. However, most of these candidate vaccines also produce unacceptable side effects—primarily mild to moderate diarrhea. An exception is strain CVD103-HgR (a mercury resistant A–B+ derivative of classical biotype Inaba serotype strain 569B). This strain has minimal reactogenicity but does not colonize well and therefore has to be given in higher doses. Field studies with this strain are in progress. Combined preparations of bacterial somatic antigen and toxin antigen have been reported to act synergistically in stimulating immunity in laboratory animals; that is, the combined protective effect is closer to the product than to the sum of the individual protective effects. However, a large field study evaluating such nonviable oral vaccines in Bangladesh revealed that neither the whole-cell bacterin nor the killed vibrios supplemented with the B-subunit protein of the cholera enterotoxin induced sufficient long term protection, especially in children, to justify their recommendation for public health use. No clear-cut advantage of the inclusion of the B-subunit was demonstrated.

In any case, even if these vaccines were effective, the requirement for large and repeated doses would make them too expensive for use in the developing areas that are usually afflicted with epidemic cholera. Moreover, they were clearly less effective in children—the primary target population in heavily endemic areas. Neither the killed whole cell vaccine nor strain CVD103-HgR could be expected to protect against the new O139 serovar.

Epidemiology

Humans apparently are the only natural host for the cholera vibrios. Cholera is acquired by the ingestion of water or food contaminated with the feces of an infected individual. Previously, the disease swept the world in six great pandemics and later receded into its ancestral home in the Indo-Pakistani subcontinent. In 1961, the El Tor biotype (a subset distinguished by physiologic characteristics) of V cholerae, not previously implicated in widespread epidemics, emerged from the Celebes (now Sulawesi), causing the seventh great cholera pandemic. In the course of their migration, the El Tor biotype cholera vibrios virtually replaced V cholerae of the classic biotype that formerly was responsible for the annual cholera epidemics in India and East Pakistan (now Bangladesh). The pandemic that began in 1961 is now heavily seeded in Southeast Asia and in Africa. It has also invaded Europe, North America, and Japan, where the outbreaks have been relatively restricted and self-limited because of more highly developed sanitation. Several new cases were reported in Texas in 1981 and sporadic cases have since been reported in Louisiana and other Gulf Coast areas. This now endemic focus appears to be due to a clone which is unique from the pandemic strain. In 1991, the pandemic strain hit Peru with massive force and has since spread through most of the Western Hemisphere, causing more than a million cases. Fortunately, mortality has been less than 1 percent because of the effectiveness of oral rehydration therapy. The vibrios surprised us again, in 1992, with the emergence of O139 in India and Bangladesh. For a while it appeared that O139 would replace O1 (both classical and El Tor) but it has exhibited quiescent periods when O1 reemerges.

Cholera appears to exhibit three major epidemiologic patterns: heavily endemic, neoepidemic (newly invaded, cholera-receptive areas), and, in developed countries with good sanitation, occasional limited outbreaks. These patterns probably depend largely on environmental factors (including sanitary and cultural aspects), the prior immune status or antigenic experience of the population at risk, and the inherent properties of the vibrios themselves, such as their resistance to gastric acidity, ability to colonize, and toxigenicity. In the heavily endemic region of the Indian subcontinent, cholera exhibits some periodicity; this may vary from year to year and seasonally, depending partly on the amount of rain and degree of flooding. Because humans are the only reservoirs, survival of the cholera vibrios during interepidemic periods probably depends on a relatively constant availability of low-level undiagnosed cases and transiently infected, asymptomatic individuals. Long-term carriers have been reported but are extremely rare. The classic case occurred in the Philippines, where “cholera Dolores” harbored cholera vibrios in her gallbladder for 12 years after her initial attack in 1962. Her carrier state resolved spontaneously in 1973; no secondary cases had been associated with her well-marked strain. Recent studies, however, have suggested that cholera vibrios can persist for some time in shellfish, algae or plankton in coastal regions of infected areas and it has been claimed that they can exist in “a viable but nonculturable state.”

During epidemic periods, the incidence of infection in communities with poor sanitation is high enough to frustrate the most vigorous epidemiologic control efforts. Although transmission occurs primarily through water contaminated with human feces, infection also may be spread within households and by contaminated foods. Thus, in heavily endemic regions, adequate supplies of pure water may reduce but not eliminate the threat of cholera.

In neoepidemic cholera-receptive areas, vigorous epidemiologic measures, including rapid identification and treatment of symptomatic cases and asymptomatically infected individuals, education in sanitary practices, and interruption of vehicles of transmission (e.g., by water chlorination), may be most effective in containing the disease. In such situations, spread of cholera usually depends on traffic of infected human beings, although spread between adjacent communities can occur through bodies of water contaminated by human feces. John Snow was credited with stopping an epidemic in London, England, by the simple expedient of removing the handle of the “Broad Street pump” (a contaminated water supply) in 1854, before acceptance of the “germ theory” and before the first isolation of the “Kommabacillus” by Robert Koch.

In such developed areas as Japan, Northern Europe, and North America, cholera has been introduced repeatedly in recent years, but has not caused devastating outbreaks; however, Japan has reported secondary cases and, in 1978, the United State experienced an outbreak of about 12 cases in Louisiana. In that outbreak, sewage was infected, and infected shellfish apparently were involved. Interestingly, the hemolytic vibrio strain implicated was identical to one that caused an unexplained isolated case in Texas in 1973.

Diagnosis

Rapid bacteriologic diagnosis offers relatively little clinical advantage to the patient with secretory diarrhea, because essentially the same treatment (fluid and electrolyte replacement) is employed regardless of etiology. Nevertheless, rapid identification of the agent can profoundly affect the subsequent course of a potential epidemic outbreak. Because of their rapid growth and characteristic colonial morphology, V cholerae can be easily isolated and identified in the bacteriology laboratory, provided, first, that the presence of cholera is suspected and, second, that suitable specific diagnostic antisera are available. The vibrios are completely inhibited or grow somewhat poorly on usual enteric diagnostic media (MacConkey agar or eosin-methylene blue agar). An effective selective medium is thiosulfate-citrate-bile salts-sucrose (TCBS) agar, on which the sucrose-fermenting cholera vibrios produce a distinctive yellow colony. However, the usefulness of this medium is limited because serologic testing of colonies grown on it occasionally proves difficult, and different lots vary in their productivity. This medium is also useful in isolating V parahaemolyticus. They can also be isolated from stool samples or rectal swabs from cholera cases on simple meat extract (nutrient) agar or bile salts agar at slightly alkaline pH values. Following observation of characteristic colonial morphology with a stereoscopic microscope using transmitted oblique illumination, microorganisms can be confirmed as cholera vibrios by a rapid slide agglutination test with specific antiserum. Classic and El Tor biotypes can be differentiated at the same time by performing a direct slide hemagglutination test with chicken erythrocytes: all freshly isolated agar-grown El Tor vibrios exhibit hemagglutination; all freshly isolated classic vibrios do not. In practice, this can be accomplished with material from patients as early as 6 hours after streaking the specimen in which the cholera vibrios usually predominate. However, to detect carriers (asymptomatically infected individuals) and to isolate cholera vibrios from food and water, enrichment procedures and selective media are recommended. Enrichment can be accomplished by inoculating alkaline (pH 8.5) peptone broth with the specimen and then streaking for isolation after an approximate 6-hour incubation period; this process both enables the rapidly growing vibrios to multiply and suppresses much of the commensal microflora.

The classic case of cholera, which includes profound secretory diarrhea and should evoke clinical suspicion, can be diagnosed within a few minutes in the prepared laboratory by finding rapidly motile bacteria on direct, bright-field, or dark-field microscopic examination of the liquid stool. The technician can then make a second preparation to which a droplet of specific anti-V cholerae O group 1 antiserum is added. This quickly stops vibrio motility. Another rapid technique is the use of fluorescein isothiocyanate-labeled specific antiserum (fluorescent antibody technique) directly on the stool or rectal swab smear or on the culture after enrichment in alkaline peptone broth. For cultural diagnosis, both nonselective and selective (TCBS) media may be used. Although demonstration of typical agglutination essentially confirms the diagnosis, additional conventional tests such as oxidase reaction, indole reaction, sugar fermentation reactions, gelatinase, lysine, arginine, and ornithine decarboxylase reactions may be helpful. Tests for chicken cell hemagglutination, hemolysis, polymyxin sensitivity, and susceptibility to phage IV are useful in differentiating the El Tor biotype from classic V cholerae. Tests for toxigenesis may be indicated.

Diagnosis can be made retrospectively by confirming significant rises in specific serum antibody titers in convalescents. For this purpose, conventional agglutination tests, tests for rises in complement-dependent vibriocidal antibody, or tests for rises in antitoxic antibody can be employed. Convenient microversions of these tests have been developed. Passive hemagglutination tests and enzyme-linked immunosorption assays (ELISAs) have also been proposed.

Cultures that resemble V cholerae but fail to agglutinate in diagnostic antisera (nonagglutinable or non-O group 1 vibrios) present more of a problem and require additional tests such as oxidase, decarboxylases, inhibition by the vibriostatic pteridine compound 0/129, and the “string test.” The string test demonstrates the property, shared by most vibrios and relatively few other genera, of forming a mucus-like string when colony material is emulsified in 0.5 percent aqueous sodium deoxycholate solution. Additional tests for enteropathogenicity and toxigenesis may be useful. Genetically based tests such as PCR are increasingly being used in specialized laboratories.

Control

Treatment of cholera consists essentially of replacing fluid and electrolytes. Formerly, this was accomplished intravenously, using costly sterile pyrogen-free intravenous solutions. The patient’s fluid losses were conveniently measured by the use of buckets, graduated in half-liter volumes, kept underneath an appropriate hole in an army-type cot on which the patient was resting. Antibiotics such as tetracycline, to which the vibrios are generally sensitive, are useful adjuncts in treatment. They shorten the period of infection with the cholera vibrios, thus reducing the continuous source of cholera enterotoxin; this results in a substantial saving of replacement fluids and a markedly briefer hospitalization. Note, however, that fluid and electrolyte replacement is all-important; patients who are adequately rehydrated and maintained will virtually always survive, and antibiotic treatment alone is not sufficient.

Recently it has been recognized that almost all cholera patients and others with similar severe secretory diarrheal disease can be maintained by fluids given orally if the solutions contain a usable energy source such as glucose. Because of this discovery, packets containing appropriate salts are distributed by such organizations as WHO and UNICEF to cholera-afflicted areas, where they are dissolved in water as needed. One such formulation, called ORS for oral rehydration salts, contains NaCl, 3.5 g; KCl,1.5 g; NaHCO3, 2.5 g (or trisodium citrate, 2.9 g); and glucose, 20.0 g. This mixture is dissolved in 1 L of water and taken orally in increments. Flavoring may be added. Improved versions of ORS, including rice-based formulations that reduce stool output and can be made at home, have been recommended. Unfortunately, this technique, which will save countless millions of lives in developing countries, has not yet been widely accepted by practicing physicians in developed countries.

The possibility of pharmacologic intervention (e.g., a pill that will stop choleraic diarrhea after it has started), has been considered. Two drugs, chlorpromazine and nicotinic acid, have been effective in experimental animals, although the precise mechanism of action has yet to be defined.

Like smallpox and typhoid, cholera—under natural circumstances—appears to affect only humans; therefore, V cholerae as an etiologic entity could conceivably disappear with the last human infection. Nevertheless, the spectrum of cholera-like diarrheal diseases probably will persist for some time.

Cholera is essentially a disease associated with poor sanitation. The simple application of sanitary principles—protecting drinking water and food from contamination with human feces—would go a long way toward controlling the disease. However, at present, this is not feasible in the underdeveloped areas that are afflicted with epidemic cholera or are considered to be cholera receptive. Meanwhile, development of a vaccine that would effectively prevent colonization and manifestations of cholera would be extremely helpful. As indicated above, such vaccines are presently being tested. Antibiotic or chemotherapeutic prophylaxis is feasible and may be indicated under certain circumstances. It also should be mentioned that the incidence of cholera is significantly higher in formula-fed than in breast-fed babies.

Present information indicates that V parahaemolyticus enteritis could be almost completely prevented by applying appropriate procedures to prevent multiplication of the organisms in contaminated seafood, such as keeping it refrigerated continually.

Other Vibrio Infections

Other vibrios may be clinically significant also. These include non-O group 1 V cholerae. Vibrio parahaemolyticus, a halophilic (salt-loving) vibrio associated with enteritis is acquired by ingestion of raw or improperly cooked seafoods. Another halophilic vibrio, which ferments lactose and for this reason was called the L + vibrio, has recently been identified as V vulnificus. It has been associated with wound infections as well as fatal septicemias. Other groups of vibrios, previously referred to as group F and EF-6, have recently been classified into species: V fluvialis, V hollisae, V furnissia, and V damsela. Vibrio mimicus is a recently described sucrose-negative species. Vibrio fetus, a group of anaerobic to microaerophilic spirally curved rods associated with venereally transmitted infertility and abortion in domestic animals, is now called Campylobacter jejuni and is considered to belong in the family Spirillaceae rather than in the family Vibrionaceae. Campylobacter jejuni has been associated with dysentery-like gastroenteritis, duodenal and gastric ulcers, as well as with other types of infection, including bacteremic and central nervous system infections in humans (see Ch. 23). Another vibrio-like organism, Helicobacter pylori (formerly known as C pylori) causes gastritis and predisposes to duodenal ulcers and gastric cancer. Although some similarities in habitat and other properties occur, members of the family Vibrionaceae are separated taxonomically from members of the family Enterobacteriaceae. The oxidase test (vibrios are usually oxidase positive) is particularly useful. Other vibrios exist, and some of these may be responsible for diseases in fish and other lower animals. As vibrios are widely distributed in the environment, particularly in estuarine waters and in seafoods, reports of their isolation from patients with diarrheal disease do not necessarily always imply an etiologic relationship.

Cholera-like vibrios have been reported in Maryland’s Chesapeake Bay but have not been associated with any human cases despite more than 15 years of extensive surveillance. These vibrios are probably nonpathogenic nonagglutinable (non-O group 1) vibrios, or the atypical O group 1 vibrios mentioned above, which do not contain the genes for toxin production, do not colonize, and are avirulent.

Relatively little is known about the epidemiology of nonagglutinable vibrios. When sought, these vibrios have been found widely in brackish surface waters (sewers, marshes, bogs, and coastal areas), and are generally more numerous in warmer months. They appear to be free-living aquatic organisms; whether particular subsets are potential pathogens is not yet clear. Strains isolated from humans with diarrheal disease more frequently give positive responses in assays for enterotoxins or enteropathogenicity, but the pathogenic mechanism of other isolates associated with shellfish remains undefined. An epidemiologic pattern is more evident with V parahaemolyticus, which is clearly part of the normal flora of coastal and estuarine waters throughout the world. Although originally recognized in Japan, V parahaemolyticus enteritis has been reported virtually worldwide within the last decade. Its reported frequency varies widely, partly because of inherent differences in distribution and partly because many laboratories do not use the appropriate culture medium (TCBS) to isolate these organisms. Two types of clinical syndromes, both usually self-limited, have been observed. The most common is a watery diarrhea, perhaps with associated abdominal cramps, nausea, vomiting, and fever, with a modal incubation period of 15 hours. A dysenteric syndrome with a short incubation period of 2 1/2 hours also has been described. In Japan, about 24 percent of reported cases of food poisoning are attributed to V parahaemolyticus. The disease occurs primarily during summer, possibly reflecting the increased presence of the organism in the marine environment during those months, as well as the enhanced opportunity for it to multiply in unrefrigerated foods. It appears to be transmitted exclusively by food, primarily raw or improperly prepared seafood. As growth of this organism is inhibited at temperatures below 15° C, rapid cooling and refrigeration of seafoods that are eaten raw would vastly reduce the incidence of disease. The organisms are killed by heating to 65° C for 10 minutes; therefore, properly handled cooked seafood should present no problem. The role played in virulence and pathogenesis by the thermostable direct hemolysin, which is responsible for the positive Kanagawa phenomenon (a hemolytic reaction around colonies growing on a particular blood agar medium), is not yet fully defined. This hemolysin is clearly associated with pathogenicity, but whether it is merely an associated marker or intimately involved in the disease process awaits further research. Be this as it may, only strains that possess the Kanagawa hemolysin are considered pathogenic. In laboratory studies, the isolated hemolysin has been reported to be cytotoxic, cardiotoxic, and lethal.

Vibrio parahaemolyticus is a curved, rod-shaped, Gram-negative bacterium found in brackish[1] saltwater, which, when ingested, causes gastrointestinal illness in humans.[1] V. parahaemolyticus is oxidase positive, facultatively aerobic, and does not form spores. Like other members of the genus Vibrio, this species is motile, with a single, polar flagellum.[2]

While infection can occur via the fecal-oral route, ingestion of bacteria in raw or undercooked seafood, usually oysters, is the predominant cause the acute gastroenteritis caused by V. parahaemolyticus.[3] Wound infections also occur, but are less common than seafood-borne disease. The disease mechanism of V. parahaemolyticus infections has not been fully elucidated.[4]

Clincal isolates usually possess two pathogenicity islands (PAI), which are acquired via horizontal gene transfer. Although the pathogenicity islands have ben sequenced, the functions of many of the PAI genes have not been elucidated. Each pathogenicity island contains a genetically-distinct Type III Secretion System, which is capable of injecting virulence proteins into host cells to cause disease. Additionally, two well-characterized virulence proteins are typically found in the pathogenicity islands, the thermostable direct hemolysin gene (tdh) or the tdh-related hemolysin gene (trh). Strains possessing the hemolysins exhibit beta-hemolysis on blood agar plates.

Epidemiology

Outbreaks tend to be concentrated along coastal regions during the summer and early fall when higher water temperatures favor higher levels of bacteria. Seafood most often implicated includes squid, mackerel, tuna, sardines, crab, shrimp, and bivalves like oysters and clams. The incubation period of ~24 hours is followed by explosive, watery diarrhea accompanied by nausea, vomiting, abdominal cramps, and sometimes fever. Vibrio parahaemolyticus symptoms typically resolve with-in 72 hours, but can persist for up to 10 days in immunocompromised individuals. As the vast majority of cases of V. parahaemolyticus food infection are self-limiting, treatment is not typically necessary. In severe cases, fluid and electrolyte replacement is indicated.

Additionally, swimming or working in affected areas can lead to infections of the eyes or ears[5] and open cuts and wounds. Following Hurricane Katrina, there were 22 vibrio wound infections 3 of which were caused by V. parahaemolyticus and 2 of these led to death.

Hopefully you have not forgotten these terminologies. Your module two on vocabulary that you studied in the first semester says that: “Blending is the fusion of two words into one, usually the first part one word with the last part of the other so that the resultant blend consists of both original meanings, e.g.: motel, brunch, fridge, smog”.

You still remember the meanings of these blendings, do you? If you don’t, study again your vocabulary lessons, will you? Clipping is a process in which a word ia formed by shortening a longer word, e.g.: zoo dorm, mag, pub, ads. You also have many clippings in Indonesian. Acronym is the result of forming a word from the first letter or letters of each word in a phrase, e.g. NASA, VIP, YMCA, AIDS. These systems of word formation are not only found in English but also in Indonesian. Look at the examples below:

Satpam, Hansip, Kanwil, Kades, Jatim, Perek.

Nur (for Nurhadi), kek (for kakek), pak (for Bapak).

KK, LSD, ABRI. AND, PBB, POMG, RSU.

It is sometime difficult, if not impossible, to find the lexical equivalent of either English blending, clipping and acronym in Indonesian or Indonesian blending, clipping and acronym in English. What is the Indonesian word for ‘motel’ or ‘brunch’? And what is the English word for ‘hansip’ or ‘Kanwil’? The easiest way to translate those words is to explain the meaning of their components, e.g.;

Thus in this case there is no word for word translation. Or, if the new word has become very popular, you don’t even have to translate it, just write as it is. For examples you have words such as NASA, UNICEF, WHO, and AIDS which you don’t have to translate because; they are quite popular. It is funny that we have etc in Indonesian which is identical with the English etc. We also have PM which can be interpreted as Perdana Perdana Menteri or Prime Minister. But these are only few coincidences.

In translating English blendings, clippings or acronyms into Indonesian you should first of all try to find the original word or words. Sometimes an acronym or a clipping has more than one meaning, thus the context will help you identify the intended one. Look at these examples below:

1. We arrived here at 7 p.m. (post maridem = sore)

2. The p.m. will be done as (post mortem = pemeriksaan mayat)

soon as the doctor arrives.

3. The British P.M. is a really tough (Prime Minister = Perdana Menteri)

woman.

4. The new P.M. has been in the (Provost Marshal = opsir tentara yang

army for more than ten years. bertugas menjaga keamanan)

5. A sub is a warship able to operate (Submarine = kapal selam)

under the surface of the sea.

6. Chris is a sub teacher for Mrs. White (Substitute = pengganti)

while she is on official leave.

7. The monument was erected by public (subscription = sumbangan)

sub.

In translating English acronyms or blendings into Indonesian sometimes you have to make lexical adjustments. Look at the examples below:

Sociolinguistics is that part of linguistics which is concerned with language as a social and cultural phenomenon. It investigates the field of language and society & has close connections with the social sciences, especially social psychology, anthropology, human geography and sociology.

Hudson (1996, p. 4) :

Sociolinguistics (micro-sociolinguistics) is the study of language in relation to society.

Sociology of language (macro-sociolinguistics)is the study of society in relation to language.

In sociolinguistics we study language and society in order to find out as much as we can about what kind of thing language is, and in the sociology of language we reverse the direction of our interest.

A variety of language as “a set of linguistic item with similar distribution,” a definition that allows us to say that all of teh following are varieties: Canadian English, London English, the English of football commentaries, and so on.

There are several possible relationships between language and society. One is that social structure may either influence or determine linguistic structure and/or behavior. A second possible relationship is directly opposed to the first: linguistic structure and/or behavior may either influence or determine social structure. A third possible relationship is that the influence is bi-directional: language and society may influence each other. A fourth possibility is to assume that there is no relationship at all between linguistic structure and social structure and that each is independent of the other.

Coulmas (1997, p. 2) :

Micro-sociolinguistics investigates how social structure influences the way people talk and how language varieties and patterns of the correlate with social attributes such as class, sex, and age.

Macro-sociolinguistics, studies what society do with their language, that is, attitudes and attachments that count for the functional distribution of speech forms in society, language shift, maintenance, nd the replacement, the delimitation and interaction of speech communities.

A. Language Variation: Focus on Users

There are four language variation that are based on its users. The first is idiolect, the second is dialect, the next is social dialect and the last is temporal dialect. The description of those language variation can be seen as follow:

1. Idiolect

Idiolect is the language variation that is individual in nature (Chaer & Agustina, 1995:82). Everyone has his own language variation or his own idiolect. This idiolect variation is concerning with the colours of voice, choice of words, language style, sentence order, etc. The colours of voice is the most dominant aspect in language variation, because we can recognize someone just by listening to voice without seeing the person.

2. Dialect

According to Spolsky (1998:33) dialect is something that concerns variations which are located regionally or socially. Dialect also means the language variation that comes from a group of users that are relative in numbers, living in one particular place, region or area (Chaer & Agustina, 1995:83). Since dialect is based on the place, region or area where the users live, it is usually called as area dialect, regional dialect or geography dialect. The users of a dialect have certain features that mark them as people who have the same dialect although they have their own idiolect. People who use Javanese with dialect of Semarang have their own particular features that are different from others who have the dialect of Surabaya. But they can communicate well with each other because those dialects are included in the same language, Javanese. The definition mentioned by (Chaer & Agustina, 1995) above is in line with what Spolsky (1998) concludes about regional dialects. He concludes that regional dialects tend to show less differences from their close neighbours and greater differences from distant neighbours (Spolsky, 1998:29).

Regional variation or regional dialect can also be found in the internatonal world. The variation can be distinguished from the pronunciation, vocabulary and even from the grammatical differences (Holmes, 2001:124). Pronunciation and vocabulary differences probably are the easiest differences that people aware of between different dialects of English. The examples of the pronunciation differences mentioned by Holmes (2001:124) in her book is the word dad pronounced by a New Zealander that to British ears sounds like dead that pronounced by an English person and the word god pronounced by an American that sounds like guard that pronounced by an English and the word latter that sounds like ladder to many non-American English speakers. The examples of the vocabulary differences can be found in the term used by Australians, people live in England and New-Zealanders. Australians use the term sole parents, while people live in England use single parents and New-Zealanders call them solo parents. South Africans use the term robot while British call exactly the same thing as traffic light. Furthermore, Holmes (2001:125) gives the example of the American vs British influence on vocabulary used in one’s region. It can be examined by using the ten questions using both American and British items. Those ten questions are:

a. When you go window-shopping do you walk on the pavement or the sidewalk?
b. Do you put your shopping in the car’s trunk or in the boot?
c. When the car’s engine needs oil do you open the bonnet or the hood?
d. Do you fill up the car with gas or with petrol?
e. When it is cold do you put on a jersey or a sweater?
f. When the baby is wet does it need a dry diaper or nappy?
g. Do you get to the top of the building in an elevator or a lift?
h. When the children are hungry do you open a can or a tin of beans?
i. When you go on holiday do you take luggage or baggage?
j. When you’ve made an error do you remove it with an eraser or a rubber?

There are eight sentences created by Holmes (2001:125) to distingushed the preferred American from the traditional British usages. Those eight sentences are:

a. Do you have a match?
b. Have you got a cigarrete?
c. She has gotten used to the noise.
d. She’s got used to the noise.
e. He dove in, head first.
f. He dived in head first.
g. Did you eat yet?
h. Have you eaten yet?

The explanation made by Holmes (2001:125) of those eight sentences are that Americans prefer to use do you have while the traditional British English use have you got, Americans use gotten while most people in England use got, many Americans use dove while most British English speakers prefer dived and Americans ask did you eat? while the English ask have you eaten?

3. Social dialect

Social dialect means the language variation that is concerning with the social status and class (Chaer & Agustina, 1995:84). This language variation is usually the most spoken language variation and most time consuming to talk about since this variation is concerning with all personal problems of the users, such as age, gender, occupation, level of royalty, economic, social status, social class, etc. According to Holmes (2001:134) social dialects are the language that reflects the groupings of people that based on similar social and economic factors. Holmes (2001:134) also states that a person’s dialect reflects his social background which can be found the complications of social dialects in Java and the ways used by Javanese speakers to show their social background. In Javanese , a particular social dialect can be defined as a particular combination of styles or levels that has its distinctive patterns of vocabulary, grammar and pronunciation. In Javanese, every time a Javanese person talks to a different person, he has to choose the right words and pronunciations because almost every word is different and they fit together in patterns or levels. A well-educated Javanese who comes from a rich family usually use five different levels of language. According to Marjohan (1988:34), the social relationship that related to status and familiarity between the Javanese speaker and the listener has to be marked. The status depends on wealth, nobility, education, occupation, age, kinship, etc. For example, in Javanese the word for house has three forms that bear status meanings, they are omah, griya and dalem.

The term social class that is related to the social dialect refers to the differences between people which are associated with differences in social prestige, wealth and education (Holmes, 2001:135). People from different social class do not speak in the same way. For example, bank managers do not talk like office cleaners, lawyers do not talk in the same way as the criminals they defend in court.

In accordance with this social dialect, there are some other language variation that people usually call as acrolect, bacilect, vulgar, slang, colloquial, jargon, argot and cant (Chaer & Agustina, 1995:87). The description of these particular language variation are in the following:

a. Acrolect. This is the social language variation that is considered to be higher or more prestigious than other social language variation (Chaer & Agustina, 1995:87). For example, the French with the dialect of the city of Paris is considered to be in the higher level than other French dialects.

b. Bacilect. It refers to the social language variation that is considered to be lower or less prestigious than other social language variation (Chaer & Agustina, 1995:87). For example, the English used by cowboys and miners can be classified into bacilect.

c. Vulgar. This means the social language variation that contains features that are used by people that are less educated or even uneducated (Chaer & Agustina, 1995:87). Languages in Europe that existed from the Romans age up to the Middle age can be classified into vulgar language since the intellectual group of people of those ages used Latin in conducting all of their activities.

d. Slang. It refers to the non-standard words that are known and used by a certain group of people, for example a group of teenagers, a group of college students, a group of jazz players, etc (Widarso, 1989:63). Since every group has its own slang words there are many kinds of slang that can be found. Slang is usually created arbitrarily, for example the word money has some slang words, such as cabbage and dough. Sometime slang words are more alive, more expressive than the standard words. For example, the slang word of cemetery is boneyard, the slang word for clerk is pencil pusher and the slang words for women who like men only because of their money are money mad and gold digger.

Slang is also related to peer group and gang speech in order to obtain some degree of secrecy (Spolsky, 1998:35). In one of the Australian aboriginal languages, exists a men’s society with a secret language in which every word means its opposite. Another example is pig Latin which is a children’s secret language using a meaningless vowel that is inserted after every syllable, like Canay uyay unayderaystanday thisay? Other social norms are also transgressed by slang, it makes free use of taboo expressions such as the words like fuck and shit in public media that has become a mark of liberation or a sign of revolt (Spolsky, 1998:36).

e. Colloquial. It means the social language variation used in daily conversation, it means the language used in speaking and not in writing (Chaer & Agustina, 1995:88). The term colloquial is derived from the word colloquium meaning conversation. The examples of colloquial in spoken English are don’t for the words do not, I’d for the words I would or I had, we’ll for we will, pretty for very, funny for peculiar and stock in for believe. Here are other examples of colloquial expression in English with their formal meanings:

1. join up => enlist
2. put up with => tolerate
3. know-how => technical skill
4. the law => a policeman
5. outside of => except
6. a natural => one who is naturally expert

f. Jargon. According to Spolsky (1998:33) it is in-group variety which serves not only to label new and needed concepts but also to create bonds among the members of a certain group and enforce boundaries for people outside the group. Hacking and surfing the net are phrases that do not have obvious meaning to people who are not following the computer revolution and sticky wicket and hit for a six are understood by people who play cricket.

Jargon also refers to the words that are known and used by a certain group of people which usually concerns with a certain field of occupation (Widarso, 1989:63). We can also say that jargon is the technical language of a particular profession. Usually it is quite easy to find the meaning of a jargon without using a special dictionary. We can see an example of jargon in the production of a motion picture. When the director wants to stop an cat of an actor, he will say Cut! and not Stop!. Other example of jargon are the terms used by sailors who use the terms starboard side to refer to the right side of a boat or ship, and port side to refer to the left side of a boat or ship.

g. Argot. This means the social variation that are limited to certain proffession only and secretly in nature by using special vocabulary (Chaer & Agustina, 2004:28). In the crime world of thieves and pick-pocketers, people in it use the terms like glasses for police, leaves for money, etc.

h. Cant. According to Chaer & Agustina (2004:28) it means the certain social variaton that is used to show poverty that is usually used by beggars, just like the expression the cant of beggars which means the language of beggars.

Spolsky (1998) has another opinion about the definition of cant. According to him, cant is the jargon used by thieves and the underworld which are used to make it hard for the outsiders to understand their conversations (Spolsky, 1998:34). However, cant is not limited to the underworld only because it can also be found in other area of occupation such as the Jewish horse traders in Alsace who have used a great number of Hebrew terms for numbers and parts of a horse to keep their language secret.

4. Temporal dialect

Temporal dialect means the language variation that is used by a certain social group in particular time (Chaer & Agustina, 1995:84). For example, the language variation can be seen in the development of English. According to Widarso (1989:22-28) the development of English had began from the Old English in the year of 600 to 1100, the Middle English in the year of 1100 to 1450, the Early Modern English in the year of 1450 to 1700 until the Modern English in the year of 1700 up to now.

B. Language Variation: Focus on Uses

In terms of language variation that are based on its uses, the discussion is focused on the ways in which speech reflects the contexts in which language is used and not the characteristics of the speakers (Holmes, 2001:223). The language variation that is concerning with the uses or functions can be called as style or register.

1. Style

For the term style, there are many definitions which are basically the same. The first to be mentioned here is the definition given by Marjohan (1988:34) that style refers to a variation in speech or writing from more formal to more casual. Some markers for the formal style would be the use of may instead of might and can and also constructions such as For whom did you get it? Instead of Who’d you get that for? in more casual speech.

Bell’s (ed. Jaworski, 1997) statement about style is in line with the statement made by Holmes (2001:223) above that style is related more with the situations than with the speakers themselves. This can be seen in his statement that when we want to talk about style, it means that we talk about the same speakers who talk in different ways on different situations and not the different speakers who talk in different ways from each other (Bell, ed. Jaworski, 1997:240).

According to Holmes (2001:246) the term style refers to language variation which reflects changes in situational factors. She also mentions that styles are often analysed according to the levels of formality (Holmes, 2001:246). This is in accordance with Martin Joos (1967) in his book The Five Clocks as quoted by Nababan (1986:22) who divides the style of formality into five levels, frozen, formal, consultative, casual and intimate styles. The description of these styles can be seen in the following:

a. Frozen style. It is the most formal style used in formal situations and ceremonies (Nababan, 1986:22). It is called frozen because the pattern has been set up firmly and can never be changed by anyone. In written form, we can see this style in historical documents, ratification, and other formal documents.

b. Formal style. It is the style used in formal speech, formal meeting, office correspendence, lesson books for school, etc (Chaer & Agustina, 1995:93). Formal style is basically similar to the frozen style that is only used in formal situations and not in informal situations. The example of formal style as quoted by Marjohan (1988:35) from Nababan (1987) is the first paragraph of the opening of the 1945 constitution of the Republic of Indonesia that was written in a formal or even in a frozen style,

c. Consultative style. This is the style used in ordinary conversation held at school, in meeting or conversation that leads to result and production (Nababan, 1986:22). It can be said that this style is the most operational one.

d. Casual style. It is the style used to speak with friends, family or relatives, during the leisure time, while exercising, etc (Chaer & Agustina, 1995:93). The casual style markers in English mentioned in Marjohan’s book (1988:35) are:

1. The absence of an article at the beginning of a sentence, for example:

e. Friend of mine saw it.
f. Coffee’s cold.

2. The absence of the subject at the beginning of a sentence, for example:

a. Bought it yesterday?
b. Makes no difference.

3. The absence of an auxiliary, for example:

a. Leaving?
b. Seen John lately?

e. Intimate style. This is the style used with people who have close relationships with the speaker (Nababan, 1986:22). By using this style those people do not need to use complete sentences with clear articulation, they just simply use short words. It happens mainly because there is an understanding among those people.

A number of kinds of style can also be found in the study conducted by Labov in 1966 as mentioned by Bell (ed. Jaworski, 1997:241) in his writing. In gathering some useful informations from his informants, Labov used a series of language tasks and recorded his interviews with them. From this recordings, he found the casual speech or the condition of paying the least attention to someone’s speech. This casual speech was used when a speaker was speaking to someone else who was not the interviewer, or discussing topics which got the speaker and that someone involved with each other. He also found another style, the careful style or the condition of paying a bit more attention to someone’s speech. This style especially revealed in the recordings when a speaker was answering questions in a typical interview way and when a speaker paid more attention to his pronunciation whenever he was asked to read aloud a brief passage of a story. Labov also found that there was the maximum amount of attention that was paid to a one’s speech whenever a speaker was asked to read out a list of isolated words and a set of minimal pairs.

Peter Trudgill (ed. Jaworski, 1997:179) used four different styles that are related to five social groups in his work on the standard ing pronunciation and the non-standard in pronunciation in Norwich English. The four styles are Word List Style (WLS), Reading Passage Style (RPS), Formal Speech (FS) and Casual Speech (CS) while the five social groups are lower working-class (LWC), middle working-class (MWC), upper working-class (UWC), lower middle-class (LMC) and middle middle-class (MMC). According to Bell (ed. Jaworski, 1997:241) from the style graph there are two things that can be revealed. The first is that when we go from the middle-class groups to the working-class groups the use of the non-standardin pronunciation increases and the use of the standarding pronunciation decreases. The second is that when each group style have to do the tasks demanding increasing attention, each group style moves from using less in to using more ing. Therefore in casual speech the five groups use most in, in careful speech and reading passage they use less in and in the word lists they use the least in.

2. Register

For the term register, according to Holmes (2001:246) it refers to the language of groups of people with common interests or jobs, or the language used in situations associated with such groups. The examples of different registers can be seen in the language used by journalist, legalist, auctioneers, race-callers, sports commentator, airline pilots, criminals, financiers, politicians, disc jockeys and also the language used in the courtroom and the classroom. One example mentioned by Holmes (2001:247) in her book the language used by people who describe a sporting event which can be distinguished easily from language used in other contexts especially in the vocabulary. In cricket, people describe positions by using terms like silly mid on, square leg, the covers and gully and describe deliveries by using terms like off-break, googly and leg break.

A variety of language marked by choices of vocabulary and used in a specific situation involving particular roles and statuses can also be considered as a register as well (Spolsky, 1998;34). The examples include a toast at a wedding, sports broadcast, or talking to a baby. As mentioned by Brown (2000:261) besides maintaining solidarity, registers are also used to identify different occupational or socioeconomic groups, that can be done in many ways, for example by looking at certain phonological variants, vocabulary, idioms or other expressions. Truckers, airline pilots, salespersons and farmers can be good examples of people who use words and phrases which are unique to their own group.

Another definition of register mentioned by Chaer & Agustina (1995:92) is that register concerns with in what activity, purpose or field a language is used for. For example the language variation used in the field of journalism, military services, scientific activities, etc. Language variation in the field of journalism has specific characteristics, it is simple, communicative and brief. The language is simple because it has to be understood easily, communicative because it has to deliver news appropriately, and brief because of the limited space (in printed media) and limited time (in electronic media).

Language variation in the field of military services has been known with its characteristics, which are brief and strict in line with the military duty and life that is full of discipline and instructions. While the scientific language has been known with its characteristics of being straight-forward, clear and free from ambiguities, metaphors and idioms because the language of science must give scientific information clearly, without any doubts, and free from possibilities of being interpreted in different meanings.

C. Application in Language Teaching

There is an interesting theory made by Bernstein in the filed of teaching that concerns with the language variation. It is called the deficit hypothesis which is based on the different language variation of the lower class and the middle class (Nababan, 1986:63). This theory states that at home children from the middle class use the language variation in a complete form (elaborated code) while children from the lower class are growing in the language variation in an incomplete form (restricted code). Since the formal language variation -which is close to the complete form of language variation used by children from the middle class, is used at schools, children from the lower class who use the incomplete form must learn the new language variation besides other subjects. It makes them tend to be less successful than children from the middle class.

There is an interesting question concerning language variation in its relation with language teaching raised by Chaer & Agustina (2004:221). The question is, should all language variation be taught? Since what should be taught is the language fact used in all interaction activities, therefore the answer to this question is supposed to be yes. Instead, there are three reasons why the non-formal styles do not need to be taught explicitly. The first reason is that in the national language policy (in the National Language Policy Seminar in 1975), it is stated that the formal style is the style which should be nurtured and developed without mentioning other non-formal styles. The second reason is that in reality the non-formal styles usually can be learned directly in daily conversations as the non-formal styles are used widely in the community. The third reason is concerning with the limited time, energy and ability of the teachers. Since time, energy and ability possessed by teachers are very limited, they should be used well to teach the formal style only. Although the non-formal styles do not need to be taught explicitly, they still need to be explained to students in order to make them understand which style is formal and which style is non-formal so that in the future they can use them in a much better and wiser way.

Pidgin and Creole Languages

Originally thought of as incomplete, broken, corrupt, not worthy of serious attention. Pidgins still are marginal: in origin (makeshift, reduced in structure), in attitudes toward them (low prestige); in our knowledge of them.
Some quick definitions:
1. Pidgin language (origin in Engl. word `business’?) is nobody’s native language; may arise when two speakers of different languages with no common language try to have a makeshift conversation. Lexicon usually comes from one language, structure often from the other. Because of colonialism, slavery etc. the prestige of Pidgin languages is very low. Many pidgins are `contact vernaculars’, may only exist for one speech event.
2. Creole (orig. person of European descent born and raised in a tropical colony) is a language that was originally a pidgin but has become nativized, i.e. a community of speakers claims it as their first language. Next used to designate the language(s) of people of Caribbean and African descent in colonial and ex-colonial countries (Jamaica, Haiti, Mauritius, Réunion, Hawaii, Pitcairn, etc.)
3. Relexification The process of substituting new vocabulary for old. Pidgins may get relexified with new English vocabulary to replace the previous Portuguese vocabulary, etc.

A creole language, or simply a creole, is some kind of sloppy French. It’s a stable language that has originated from a pidgin language that has been nativized (that is, acquired by children). The vocabulary of a creole language consists of cognates from the parent languages, though there are often clear phonetic and semantic shifts. On the other hand, the grammar often has original features but may differ substantially from those of the parent languages. Most often, the vocabulary comes from the dominant group and the grammar from the subordinate group, where such stratification exits. For example, Jamaican Creole features largely English words superimposed on West African grammar.

A creole is believed to arise when a pidgin, which was developed by adults for use as a second language, becomes the native and primary language of their children — a process known as nativization.

Diglossia

In linguistics, diglossia (pronounced /daI’ɡlɒsiə/, from Greek: διγλωσσία < δύο+γλώσσα, two languages) refers to a situation in which two dialects or languages are used by a single language community. In addition to the community's everyday or vernacular language variety (labeled "L" or "low" variety), a second, highly codified variety (labeled "H" or "high") is used in certain situations such as literature, formal education, or other specific settings, but not used for ordinary conversation.

Post-1959 research on diglossia has concentrated on a number of variables and important questions: function, prestige, literary heritage, acquisition, standardization, stability, grammar, lexicon, phonology, the difference between diglossia and standard-with-dialects, extent of distribution in space, time, and in various language families, and finally what engenders diglossia and what conditions favor its development.
1. Function. The functional differentiation of discrepant varieties in a diglossia is fundamental, thus distinguishing it from bilingualism. H and L are used for different purposes, and native speakers of the community would find it odd (even ludicrous, outrageous) if anyone used H in an L domain, or L in an H domain.
2. Prestige: in most diglossias examined, H was more highly valued (had greater prestige) than was L. The H variety is that of `great' literature, canonical religious texts, ancient poetry, of public speaking, of pomp and circumstance. The L-variety is felt to be less worthy, corrupt, `broken', vulgar, undignified, etc.
3. Literary Heritage: In most diglossic languages, the literature is all in H-variety; no written uses of L exist, except for `dialect' poetry, advertising, or `low' restricted genres. In most diglossic languages, the H-variety is thought to be the language; the L-variety is sometimes denied to exist, or is claimed to be only spoken by lesser mortals (servants, women, children). In some traditions (e.g. Shakespeare's plays), L-variety would be used to show certain characters as rustic, comical, uneducated, etc.
4. Acquisition: L-variety is the variety learned first; it is the mother tongue, the language of the home. H-variety is acquired through schooling. Where linguists would therefore insist that the L-variety is primary, native scholars see only the H-variety as the language.
5. Standardization: H is strictly standardized; grammars, dictionaries, canonical texts, etc. exist for it, written by native grammarians. L is rarely standardized in the traditional sense, or if grammars exist, are written by outsiders.
6. Stability: Diglossias are generally stable, persisting for centuries or even millennia. Occasionally L-varieties gain domains and displace the H-variety, but H only displaces L if H is the mother tongue of an elite, usually in a neighboring polity.
7. Grammar: The grammars of H are more complex than the grammars of L-variety. They have more complex tense systems, gender systems, agreement, syntax than L-variety.
8. Lexicon: Lexicon is often somewhat shared, but generally there is differentiation; H has vocabulary that L lacks, and vice-versa.
9. Phonology: Two kinds of systems are discerned. One is where H and L share the same phonological elements, but H may have more complicated morphophonemics. Or, H is a special subset of the L-variety inventory. (But speakers often fail to keep the two systems separate.)
A second type is one where H has contrasts that L lacks, systematically substituting some other phoneme for the lacking contrast; but L may `borrow' elements as tatsamas, using the H-variety contrast in that particular item.
10. Difference between Diglossia and Standard-with-dialects. In diglossia, no-one speaks the H-variety as a mother tongue, only the L-variety. In the Standard-with-dialects situation, some speakers speak H as a mother tongue, while others speak L-varieties as a mother tongue and acquire H as a second system.
11. Distribution of diglossia in language-families, space, and time. Diglossia is not limited to any geographical area or language family, and diglossias have existed for centuries or millennia (Arabic, South Asia). Most diglossias involve literacy, but oral diglossias are conceivable.
12. What engenders diglossia and under what conditions.
(a) Existence of an ancient or prestigious literature, composed in the H-variety, which the linguistic culture wishes to preserve as such.
(b) Literacy is usually a condition, but is usually restricted to a small elite. When conditions require universal literacy in H, pedagogical problems ensue.
(c) Diglossias do not spring up overnight; they take time to develop
These three factors, perhaps linked with religion, make diglossia extremely stable in Arabic and other linguistic cultures such as South Asia.

Bilingualism and Multilingualism

A bilingual individual, generally, is someone who speaks two languages. An ideal or balanced bilingual speaks each language as proficiently as an educated native speaker. This is often referred to as an ideal type since few people are regarded as being able to reach this standard. Otherwise, a bilingual may be anywhere on a continuum of skills.

A multilingual person, in a broad definition, is one who can communicate in more than one language, be it actively (through speaking, writing, or signing) or passively (through listening, reading, or perceiving). More specifically, the terms bilingual and trilingual are used to describe comparable situations in which two or three languages are involved. A generic term for multilingual persons is polyglot. Poly (Greek: πολύς) means “many”, glot (Greek: γλώττα) means “language”.
Multilingual speakers have acquired and maintained at least one language during childhood, the so-called first language (L1). The first language (sometimes also referred to as the mother tongue) is acquired without formal education, by mechanisms heavily disputed. Children acquiring two languages in this way are called simultaneous bilinguals. Even in the case of simultaneous bilinguals one language usually dominates over the other. This kind of bilingualism is most likely to occur when a child is raised by bilingual parents in a predominantly monolingual environment. It can also occur when the parents are monolingual but have raised their child or children in two different countries.

Code-switching

In linguistics, Code-switching is the concurrent use of more than one language, or language variety, in conversation. Multilinguals – people who speak more than one language – sometimes use elements of multiple languages in conversing with each other. Thus, code-switching is the syntactically and phonologically appropriate use of more than one linguistic variety.
Code-switching is distinct from other language contact phenomena, such as borrowing, pidgins and creoles, loan translation (calques), and language transfer (language interference). Speakers form and establish a pidgin language when two or more speakers who do not speak a common language form an intermediate, third language. On the other hand, speakers practice code-switching when they are each fluent in both languages. Code mixing is a thematically related term, but the usage of the terms code-switching and code-mixing varies. Some scholars use either term to denote the same practice, while others apply code-mixing to denote the formal linguistic properties of said language-contact phenomena, and code-switching to denote the actual, spoken usages by multilingual persons.

Types of switching

Scholars use different names for various types of code-switching.
• Intersentential switching occurs outside the sentence or the clause level (i.e. at sentence or clause boundaries).
• Intra-sentential switching occurs within a sentence or a clause.
• Tag-switching is the switching of either a tag phrase or a word, or both, from language-B to language-A, (common intra-sentential switches).
• Intra-word switching occurs within a word, itself, such as at a morpheme boundary.

Speech community

Speech community is a group of people who share a set of norms and expectations regarding the use of language. Speech communities can be members of a profession with a specialized jargon, distinct social groups like high school students or hip hop fans (see also African American Vernacular English), or even tight-knit groups like families and friends. In addition, online and other mediated communities, such as many internet forums, often constitute speech communities. Members of speech communities will often develop slang or jargon to serve the group’s special purposes and priorities.

DefinitionExactly how to define speech community is debated in the literature. Definitions of speech community tend to involve varying degrees of emphasis on the following:
• Shared community membership
• Shared linguistic communication
However, the relative importance and exact definitions of these also vary. Some would argue that a speech community must be a ‘real’ community, i.e. a group of people living in the same location (such as a city or a neighborhood), while more recent thinking proposes that all people are indeed part of several communities (through home location, occupation, gender, class, religious belonging, and more), and that they are thus also part of simultaneous speech communities.
Similarly, what shared linguistic communication entails is also a variable concept. Some would argue that a shared first language, even dialect, is necessary, while for others the ability to communicate and interact (even across language barriers) is sufficient.

Variation Studies: Some Findings and IssuesAn Early Study
One of the earliest studies of variation was Fischer’s study (1958) of the (ng) variable, i.e., pronunciations like singing [ŋ] versus singin’ [n]. There is a long history of both the [ŋ] and [n] variants in the language, that stigmatization of the [n] variant is a phenomenon of the nineteenth and twentieth centuries, and that even today in some circles in the United Kingdom, necessarily privileged ones, people still go huntin’, shootin’, and fishin’, not hunting, shooting, and fishing.
As part of a study of child-rearing in a New England community, Fischer conducted interviews with young children, twelve boys and twelve girls, age 3-10. He noted their use of [ŋ] and [n] in a very formal situation during the administration of the Thematic Apperception Test, in a less formal interview, and in an informal situation in which the children discussed recent activities. In table below shows that boys use more –in’ forms than girls in the most formal situation.
Preferences for –ing and –in’ endings, by sex

-ing > -in’ -ing < -in’
Boys 5 7
Girls 10 2
Fischer also compared the use of [ŋ] and [n] of a boy described by his teachers as a ‘model’ boy with that of a boy described as a ‘typical’ boy. The model boy worked well in school and was described as being popular, thoughtful, and considerate; the typical boy was described as being strong, mischievous, and apparently unafraid of being caught doing something he should not be doing. In the most formal situation these two boys produced the number of instances of -ing and –in’ reported in table below.
Preferences of two boys for –ing and –in’ endings

-ing -in’
‘Model’ boy 38 1
‘Typical’ boys 10 12
However, Fischer further observed that the model boy also use –in’ more as the formality of the situation decreased, as we can see in table below.
Preferences for –ing and –in’ endings, by formality of situation

Most formal Formal interview Informal interview
-ing 38 33 24
-in’ 1 35 41
He observeb several other interesting facts. As children relaxed in the most formal situation they produced more instances of –in’ . Such usage was also associated with specific verbs so that verbs like hit, chew, swim, and punch, i.e., verbs describing everyday activities were much more likely to be given –in’ endings than more ‘formal’ verbs like criticize, correct, read and visit. Fischer’s conclusion is that ‘the choice between the –ing and the –in’ variants appears to be related to sex, class, personality (aggressive/cooperative), and mood (tense/relaxed) of the speaker, to the formality of the conversation and to the specific verb spoken’.

A Variety of Studies
The Detroit study (Shuy et al., 1968) and Wolfram’s follow-up to that study (1969) hav esome findings which are worthy of comment in the present context. For example, the Detroit study investigated the use of multiple negation as a linguistic variable in that city. The study showed that there is a very close relationship between the use of multiple negation and social class.
Wolfram’s general findings in Detroit were that social status was the single most important variable correlating with linguistic differences, with the clearest boundary being between the lower middle and upper working classes. In each class, however, females used more standard-language forms than males. Older subjects also used fewer stigmatized forms than did younger subjects. Finally, reading style showed the fewest deviations of all from standard-language forms.

Controversies
I noted that linguistic variables may show correlations not only with social variables but also with other linguistic features, i.e., they may be linguistically constraint too, as with the deletion of l in Montreal. In their discussion of linguistic variation, Wolfram and Fasold (1974, pp. 101-5) present data from an earlier study by Fasold (1972) to show that it is possible to state how two or more factors, or constraint, interact to affect the distribution of a variable. In this case they are concerned with deletion of final stop in clusters, e.g., the d in the word like cold, in speech among blacks in Washington, DC. The data showed that the parenthesized stop were deleted as follows: san(d) castle, 83.3 percent deletion; fas(t) car , 68.8 percent deletion; wil(d) elephant, 34.9 percent deletion ; and lif(t) it, 25.2 percent deletion. If we look closely at the environments of these stops, we will find that sometimes the stop is preceded by a sonorant (a nasal or l) and sometimes by a non-sonorant ( a stop or a fricative), and it is followed sometimes by a vowel and sometimes by a consonant (or non-vowel).

Language change
Linguists have traditionally studied variations in a language occurring at the same, time (synchronic study) or how language develops over time (diachronic or historical study). Both can be useful aids to understanding.
The study of language change is often narrowed to consideration of change in one aspect of language: lexis, semantics or syntax, say. But you should have a sense of the broad historical development of English. Later, you may wish to study more fully how the language developed at a particular period. For the 20th century, we are able to study some kinds of change over a very short time, as there is plenty of evidence. The further back we go, the longer may be the periods over which change can be observed. Before the 20th century, most of the evidence that survives is of written forms. We have some second-hand written evidence of spoken language forms, but no recorded speech earlier than that allowed by modern recording technology.

Studying standardization and change by language category
Although a chronological model gives us a sense of succession and of history as narrative, it can make it hard to see the theory or outline of a question or contemporary opinion. It can also lead us to see historical divisions (the end of a century) as having more importance than is really the case. In what follows aspects of change and standardization are considered in terms of language categories. Some of these will affect spoken or written English only (e.g. phonology or spelling, respectively) while others (lexis, semantics, syntax) are common to both or (like style) affect both but possibly in different ways.

Grammar
Models or examples that we imitate may become real or de facto standards. Texts with a large audience may thus create patterns to which we conform. Prescriptive rules are compiled because the writer presumably wishes to “correct” some real language tendency – these invented rules (akin to matters of etiquette or table manners) are likely to fail, but may in the meantime promote social attitudes about “correct” or “incorrect” English that are confused with genuine rules.
Some “rules”, like those drawn up by Lowth in 1762, have acquired currency: for example, that one should not put a preposition at the end of a sentence, use double or multiple negatives, split the infinitive, or use they as a gender-neutral pronoun. Professor R.W. Zandvoort describes how English usage ignores these pseudo-rules, while Jean Aitchison in her lecture A Web of Worries gives historical and modern examples to show what Zandvoort describes.

Lexis and semantics
This is less problematic or, rather, the problems are readily grasped. Some lexical items with some meanings are certainly standard features of English at a given time – the OED is full of them. Equally, some other items are obviously not standard or have n/s meanings. And many items are in the process of becoming or ceasing to be standard. Thus, in spite of continual language change, we can create a standard lexicon at any time. We can take this further and show how a given lexical item with a given meaning may be standard in a given context or within a variety but be n/s as regards the mainstream.
For example Hoover began life as a brand name, a proper-noun equivalent to generic vacuum cleaner. Nowadays, in spoken UK English Hoover or arguably hoover is acceptable as a generic name or common noun. At the turn of the century supplements to the OED recorded various forms of Kodak (small portable camera) including kodaker (photographer) and kodakry photography. These are no longer standard although Polaroid is acceptable to denote the instant photographs produced in such cameras.
Both lexis and semantics (especially semantic change or drift) may be culturally determined. They may depend on some other thing (a process or object) which ceases to be familiar, and so the word disappears or the meaning shifts. This has happened to words like wireless, telegram or terms from imperial measurement and pre-decimal currency (foot, inch, gallon, bushel, halfpenny [do you know the standard pronunciation of this?], and shilling.

Spelling
Discussion of spelling is bedevilled by strong social attitudes. Even teachers, who should know better, characterize n/s spelling by epithets such as “bad”, “poor”, “awful” or “appalling” – as if the writer wilfully ignored the standard form. The National Curriculum draws attention to many other features of written performance as well as spelling, but the social attitudes persist. Yet Chaucer, Shakespeare and Milton (necessarily) wrote without regard to a standard, so standard spelling can hardly be a measure of merit. The allegation that n/s spelling confuses the reader is often false (as with n/s omission or adding of a second consonant or n/s e before -ing in verbs). Non-standard spellings used in marketing (Kwik Fit, Kwik Save, Toys R Us) rarely appear unintentionally in children’s writing, as any teacher knows. On the other hand, the commonest “errors” such as alot for (standard) a lot, grammer for (standard) grammar or belive for standard believe all make clear what the writer intends.
Johnson’s dictionary establishes a standard because it is not prescriptive but descriptive. It records what is in Johnson’s (very wide) reading the most common form, making allowance for consistency of like elements, and showing etymology, for those who know other languages. Thus cede (verb=give, from Latin) and seed (noun) are differently spelt though homophones (having more or less the same sound value). Johnson also disarms critics by quoting usage, not merely laying down a preferred form.
The modern reader sees Noah Webster’s variants as distinctly American (ax, color, plow, theater, waggon) but often Webster has recorded an older English form than Dr. Johnson.

Punctuation
Punctuation, which may be more critical to communicating meaning than spelling, provokes much less strong social attitudes – perhaps because n/s forms are less obvious, perhaps because punctuation has no defining moment like the publication of Johnson’s dictionary, but has evolved gradually and has standard forms but is open to change.
From the 18th century onwards one sees most punctuation marks which are considered standard today. Some have changed their use – in general, late 20th century texts, especially non-literary texts, have less frequent use of marks which are deemed optional. In modern German, a comma to separate clauses is obligatory, but not in English. Businesses use so-called “open punctuation” of addresses (no comma after each element). In many cases ignorance or confusion about conventions may cause writers to avoid some marks: the semi-colon and colon are problematic, while the great difference of function between hyphen and dash may be confused by lack of difference in appearance: on a typewriter the same key served for both (some typists would repeat the stroke for a dash). Some modern computer software restores the difference, where the grammar checking can detect that the context calls for the (longer) dash. (HTML character sets seem not to distinguish between the hyphen and dash, so I can’t show you the difference in appearance here.)
Some writers may have caused punctuation marks to lose impact by over-use. Teachers will be familiar with multiple exclamation marks, or with exclamation marks in contexts where only mild emphasis is intended.

Phonology
Before the advent of modern recording and broadcasting technology debate about sounds was reliant on written transcripts, which could at best approximate to real phonology. Much is made of inference from, for example, rhyming words in poetry – did the poet use imperfect rhyme or have sounds changed in, for example, John Donne’s “And find/What wind/Serves to advance an honest mind”. Does US (rhymes with lurk) or UK (rhymes with dark) pronunciation of clerk preserve the older English form – or have two rival sounds fared differently in separate locations? And what of lieutenant? US loo-ten-unt (with stress on first or second syllable) is closer to the French original than UK lef-ten-unt (stress on second syllable).
The various phonetic alphabets give a symbolic representation of sounds that are described in terms of physical performance (for example the position of tongue relative to teeth). Modern recording technology can be used to give a far more precise and objective description of a sound produced, as a waveform or a measure of frequency and so on.
As sound recording is now more than a century old, we can observe change and standardizing tendencies in spoken English. Received Pronunciation (RP) is a notional standard form of pronunciation. RP is associated with prestige and formal public spoken discourse, such as the law, parliament, education or broadcasting. In some of these it may be in tension with regional variations. RP currently is a modified form of the accent heard in independent and grammar schools or spoken by newsreaders; the accent is largely neutral as regards region, but long/soft vowels are preferred to hard/short vowel sounds. Listening to a recording of a broadcast from an earlier period (a Pathé newsreel or Alvar Liddell [an early BBC radio broadcaster] reading the news for the BBC) will show how far RP has changed over time – the earlier RP survives in part in the accent of Queen Elizabeth II, who speaks with much less clearly differentiated (or less open) vowels than the modern RP speaker (the stiff upper lip is literal as well as a metaphor). Our notion of RP in earlier times may also derive from the accents heard in UK feature films (think of Celia Johnson in Brief Encounter). We have no easy way of knowing how far this corresponded to the prestige accent of the time.

Invented rules
You may understand this subject better by looking at some invented rules. These are not descriptions of general usage but inventions of Robert Lowth and others. Some of them have so influenced past generations that they are accepted as normative. Here are examples of some of the more commonly-encountered pseudo-rules.

They and them are not to be used as singular pronouns.

Example: If anyone calls, tell them I’m in a meeting.
Comment: Such use may be inelegant style but does not break any real rule of grammar. Professor R.W. Zandvoort (The Fundamentals of English Grammar – Arnold’s Card Guides; London, 1963) says, “Where sex is unknown he or they may be used of an adult, he or it of children”. Jean Aitchison (The Language Web, p. 8) quotes examples from the 18th century to the present day of writers who disregard this “rule”, including William Thackeray, Lewis Carroll, Virginia Woolf and George Bernard Shaw.

The infinitive should not be split (separated from to by a qualifier)

Example: The mission was to boldly go where no man had ever gone before.

Comment: There is no justification at all for this supposed rule.

Double negatives are really affirmatives.
Example: I don’t know nothing about that.
Comment: This derives from Robert Lowth (“Two negatives… are equivalent to an affirmative”) but is deeply entrenched in popular attitudes to language. It arises from confusing vernacular languages with logic or theory of number. Now the double negative is often used to signal an affirmative, but indirectly, as in that’s not unreasonable. Aitchison finds a multiple (fourfold) negative for emphatic negation in Chaucer’s General Prologue to the Canterbury Tales. Of the knight, we are told he never yet no vileynye ne sayde
In al his lyf unto no maner wight
(He never even no wicked thing not said in all his life to no kind of person).

Different should be immediately followed by “from” (not “than” or “to”)
Comment: Aitchison finds examples of different to and H.W. Fowler’s Modern English Usage labels the preference for different from a “superstition”. But different to and different than may have other distinct uses. Consider these examples:
• After the room was painted it looked different to me.
• After the room was painted it looked different from how it did before.
• A dog is different from a wolf. A slug is different from a wolf. But a slug is more different than a dog from a wolf.
Most prepositions function in ways that are not coherent or logical. Many languages do not have them. Since their use is a matter of convention, the idea of style or fitness (as with the double negative) may now argue against different to.

Prepositions should not come at the end of a sentence.
Example: This is the man who/that I spoke to.
(Preferred form given as This is the man to whom I spoke.)
Comment: The suggestion that the preposition should come before the verb phrase has no justification. The second example above may be more elegant, but rigid enforcing of the “rule” can have the opposite effect, as in the notorious: This is English, up with which I will not put.

Quizzes
Dates and events
If you want to learn important events and their dates, click on the link below for a short quiz. Why do this? You may want to be confident, before taking an exam, that you know what happened when.
• Take a quiz on important dates in the history of English

Learn about the lexicon
If you want to learn about the English lexicon, click on the link below for a short quiz. Why do this? You may want to be confident, before taking an exam, that you know examples of lexis which have entered English from different languages.
• Take a quiz on the etymology of English words.
Take a general language change quiz
Click on the link below for a general quiz on language change – some questions are not yet covered by this guide: you may need to look elsewhere to find out more. Many thanks to Terry of South Downs and the English Language List for sharing this quiz.
• Take a quiz on language change

An essay is a piece of writing several paragraphs long instead of just one paragraphs. It is written about one topic, just as a paragraph is. However, the topic essay is too long and too complex to discuss in one paragraph. Therefore, you divide the topic into several paragraphs, one for each major point. Then you must of the separate paragraphs together by adding an introduction and a conclusion.

Writing an essay is no more difficult than writing a paragraph except the essay is longer. The principles of organization are the same for both, so if you can a good paragraph, you can write a good essay.

An essay has three main parts:
1. An introductory paragraph
2. A body (at least one, but usually two or more paragraphs)
3. A concluding paragraph

The introductory paragraph consists of two parts: a few get statement about your subject to attract your reader’s attention and the statement to state the specific subdivision of your topic and/or the “plan” of paper. A thesis statement for an essay is just like a topic sentence for a paragraph.

The body consists of one or more paragraphs. Each paragraph developed subdivision of your topic, so the number of paragraphs in the body will vary with number of subdivisions. The paragraphs of the body are like the main support points of a paragraph. Furthermore, just as you can organize the ideas in a paragraph chronological order or by order of importance, you can organize the paragraphs in essay in the same ways.

The conclusion in an essay, like the concluding sentence in a paragraph, summary or review of the main points discussed in the body.

The only additional element in an essay is the linking expressions between the paragraphs of the body. These are just like transitions within a paragraph. You use transitions within a paragraph to connect the ideas between two sentences. Similarly, you use transitions between paragraphs to connect the ideas between them.

All writers (even professionals) complain that the most difficult part writing getting trying to think of your first sentence? Getting started, or writing introduction, can be easy if you remember that an introduction has four :
1. It introduces the topic of the essay.
2. It gives a general background of the topic.
3. It often indicates the overall “plan” of the essay.
4. It should arouse the teacher’s interest in the topic.

The introduction has two parts:
1. General statements
2. A thesis statement

General statements:
1. Introduce the topic of the essay.
2. Give background information on the topic.

The thesis statement:
1. States the main topic.
2. List the subdivisions of the topic.
3. May indicate the method of organization of the entire paper.
4. Is usually the last sentence in the introductory paragraph.

The Concluding Paragraph

This paragraph should include the following:
1. an allusion to the pattern used in the introductory paragraph,
2. a restatement of the thesis statement, using some of the original language or language that “echoes” the original language. (The restatement, however, must not be a duplicate thesis statement.)
3. a summary of the three main points from the body of the paper.
4. a final statement that gives the reader signals that the discussion has come to an end. (This final statement may be a “call to action” in an persuasive paper.)

Transition signals between paragraphs

Transition signals are important not only within paragraphs but also between paragraphs. If you write two or more paragraphs, you need to show the relation between your first and second paragraph, between your second and third paragraph and so on.
Think of transitions between paragraphs as the links of chain. The linkage chain connect the chain; they hold it together. Similarly, a transition signal between two paragraphs links your ideas together.
Two paragraphs are linked by adding a transition signal to the topic sentence the second paragraph. This transition signal may be a single word, a phrase dependent clause that repeats or summarizes the main idea in the first paragraph.

Writing and revising the essay

You were introduced to writing and revising drafts of a single paragraph, important steps in the writing process. You learned that writing a good paragraph takes time and effort. You were also taken through the steps of the revision process by studying the drafts of the model paragraph.
Just as you wrote several drafts of your paragraphs before your final copy, you will also continue to write and revise several drafts of your essays until you have produced a final copy that you can be proud of.

Parts of an Essay

1. The Introduction opens the essay. It is a short paragraph – usually about THREE sentences.

In an argument essay, it usually describes or summarizes both sides of the present situation and says what you are going to do in your essay.

2. The Body is the main part of the essay. In an argument essay, it is divided into two or three paragraphs, giving your opinion and reasons.

Each paragraph in the body is between FIVE and SEVEN sentences long.

3. The Conclusion is the end of the essay. It is a short paragraph – about THREE sentences. It often has the same idea as the Introduction, only in different words.

A paragraph is a basic unit of organiazation in writing in which a group of related sentences developes one main idea. A paragraph can be as short as one sentence or as long as ten sentences. The number of sentences is unimportant; however, the paragraph should be long enough to develop the main idea clearly.

The Three Parts of a Paragraph

A paragraph has three major structural parts:

1. The topic sentence states the main idea of the paragraph. It not only names the topic of the paragraph, but it also limits the topic to one or two areas that can be discussed completely in the space of a single paragraph. The specific area is called the controlling idea.
eg. Gold, a precious metal, is prized for two important charateristics.
Gold -> topic
two important charateristics -> controlling idea

Every good sentence has a topic sentence, which clearly states the topic and the controlling idea of the paragraph. It is a complete sentence. It is usually (but not always) the first sentence in the paragraph.
A topic sentence is the most important sentence in a paragraph. It briefly indicates what the paragraph is going to discuss.

There are three important points to remember about the topic sentence:
– A topic sentence is a complete sentence; that is, it contains a subject, a verb, and (usually) a complement.
– A topic sentence contains both a topic and a controlling idea. It names the topic and then limits the topic to a specific area to be discussed in the space of a single paragraph.
– A topic sentence is the most general statement in the paragraph because gives only the main idea. It does not give any specific details.

3. The concluding sentence signals the end of the paragraph and leaves the reader with important points to remember. A concluding sentence is not absolutely necessary; in fact, a concluding sentence is not customary for every paragraph in a multiparagraph essay.

A concluding sentence sentence serves three purposes:
– It signals the end of the pargraph
– It summerizes the main points of paragraph
– It gives a final comment on your topic and leaves the reader with the most important ideas to think about

Unity and Coherence

In addition to the three structural parts of a paragraph, a good paragraph also has the elements of unity and coherence.

Unity means that you discuss only one main idea in a paragraph. The main idea is stated in the topic sentence, and then each and every supporting sentence develpos that idea.

Coherence means that your paragraph is easy to read and understand because (1) your supporting sentences are in some kind of logical order and (2) your ideas are connected by the use of appropriate transition signals.

Subnet Mask
A subnet mask is a number that looks like an IP Address. It shows TCP/IP how many bits are used for the network portion of the IP Address by covering up, or “masking” the IP Address’s network portion.